Evaporators and condensers are devices e.g. used for heat exchangers, such as slender tube heat exchangers, plate type heat exchangers, spiral heat exchangers and etc. In a heat exchanger according to the plate type, the media circulates inside alternating plates, typically made of metal and brazed together with sealed inlets and outlets forming closed duct systems within a package of interacting, interconnected, plates in which the media circulate under heat exchange. The published patent application WO003189 describes such a plate type heat exchanger in more detail.
FIG. 1 illustrates the working principle of a conventional heat exchanger with a compressor driven evaporation process. Such a heat exchanger includes an evaporation chamber 110′, a compressor 120′, a condenser chamber 130′ and an expansion valve 140′.
As is well known in the art, the cooling medium in the evaporation chamber 110′ absorbs heat Qin, and thereafter evaporates whereupon it is directed to the compressor 120′, and then further directed to the condenser chamber 130′ where the medium emits heat Qout and condenses. The medium is then fed back to the evaporation chamber 110′ through the expansion valve 140′.
During operation, the cooling medium coming from the expansion valve 140′ enters the evaporation chamber 110′ through the inlet of the evaporation chamber 110′, and the cooling medium absorbs heat and evaporates, and then the evaporated medium enters the compressor.
A concern with the heat exchanger relates to the fact that since the cooling medium in the evaporator is distributed in several parallel evaporation chambers, the cooling medium is in two phases (liquid and gas) and the cooling capacity mainly depends on the cooling medium in liquid state, it's important that the velocity of the liquid medium is equal in each evaporation chamber. Furthermore the velocity of the cooling medium in gas state will create main part of the pressure drop. Normally in an evaporator such as that show in FIG. 1, the evaporation chambers are separated from each other and this makes it difficult to stabilize the liquid medium velocity in each evaporation chamber.
Furthermore lubricant oil will be accumulated in the lower part of the evaporation chamber and will stall around corner of the lower part of the evaporation chamber and does not fully mix with the cooling medium, so only a small part of the lubricant oil is entrapped in the evaporated medium and is brought into the compressor, and this will cause damage to the compressor, because most of the lubricant oil can not reach the compressor, and thus the compressor may be in a condition of lack of lubricant oil, resulting in the reduction of the use life of the compressor and some other problems.